The field of the invention is processing semiconductor wafers and similar flat articles or workpieces, such as memory media, optical media and masks, micro-electronic or micro-mechanical substrates, and similar flat workpieces, collectively referred to here as wafers.
Wafer processing requires a very clean environment, as even low levels of contaminants or microscopic contaminant particles can degrade or destroy performance of the wafer end products, which are typically micro-electronic products. Various systems and methods have been developed for handling and processing wafers, while attempting to minimize the potential for contamination or damage to the wafers.
Various manufacturing steps involve spraying process liquids and/or gases onto the wafers. The process chemicals are often sprayed onto the wafers while the wafers are spinning, to assist in distribution of the chemicals over the wafer surfaces. With this type of processing, the amount of structure or material between the wafers and the spray nozzles is advantageously minimized, so that the spray nozzles can spray process chemicals directly onto the wafers, through or past a minimum amount of obstructions. On the other hand, at least some supporting structure is required to support the wafers during processing. During stationary processing, at a minimum, the wafers must, of course, be supported from below. During spin processing, the wafers must be supported from both above and below, or on opposite sides, to avoid excessive wafer movement within the rotor or other wafer holder, as the wafers rotate.
To meet these needs, centrifugal or spin processors have included rotors with large open areas, to reduce blocking or obstructing the process chemicals sprayed towards the wafers.
On the other hand, during movement of the wafers into, out of or between process chambers or storage positions, having additional structure around the wafers is advantageous, to better protect the wafers from physical damage, or to protect a single wafer within a batch or array of wafers, from potential damage by a misplaced or broken adjacent wafer. Consequently, these competing or contrary requirements present engineering challenges in the design of wafer processing systems and methods. As wafer processing ordinarily is performed in a clean room, the processing system advantageously is compact, to reduce space and manufacturing costs. Accordingly, it is an object of the invention to provide an improved system and methods for handling wafers, and for processing wafers. Other objects, features and advantages will appear below.